Semiautomatic telephone system



June 3Q. 1925. 1,543,685 R. L. STOKELY SEMIAUTOMATIC TELEPHONE SYSTEMFiled July 1, 1921 6 Sheets-Sheet 2,

June 30, 1925.

R. L. STOKELY SEMIAUTOMATIO TELEPHONE SYSTEM Filed July 1, 1921 6Sheets-Sheet 3 Mrenfor Edy L. Sic/way June 30, 19254 1,543,685 R. L.STOKELY sEMIAumoMATIc mswvuous svsma Filed July 1, 1921 a Sheets-Sheet 41 "i 1 Mqrginal lnven/br:

Jun; 30, 1925.

R. L. ST OKELY SEIIAUTOMATIC TELEPNQNE SYSTEI Filed July 1. 1921 sSheets-'Sheet s lnvenfol':

Bay L; dfolcey' June 30-, 19254 R. L. STOKELY SEMIAU'I' MA'I'TCTELEPHONE SYSTEM 6 Sheet-Sheet 5 Filed July 1, 1921 lrzvenfor: Bay A.fifokefy Patented June 39, 1925. i it I nun-ED STATE-5 PATENT oFFics.

nae L. streamer, on FLO RAL Penn; roan, 'ro' wnsrnnn nntccriarccorarnnr. INwRPoBn'rn-n, ornnw Ycnn, n. a conrcancriori on NEW YORK.

SEIv'IIAUillOMATIQ TELEIEH-QNE SYSTEM.

A ication "rila m 1,

To all whom it may concern. Be it known that I RiAY L. STOKELY, acitizen of the United States, residing at Floral Park, in the county ofNassau, State of New York have. invented certain new and usefulImprovements in Semiautoma-tic Telephone Systems,"of which the followingis a fulhjclear, concise and exactdescription.

This invention relates to semi-automatic telephone systems and moreparticularly to tell switching trunk circuits. 5 Theobject of the;inrent ion is to provide an improved arrangement for systems of thischaracter. 7

One oglithe features of this invention is the provision of inanual meansfor associating a calling device with a trunk leading to an automaticofti'ce,. and means for auto matically disconnecting. the calling devicefrom thetrunk as soon as the. connector reaches the called lineterminals whereby the calling device is immediately released for use in.other calls. i

Another feature is, the provision of means for automatically operating.a supervisory signal. before the operator as. soon as the calling deviceis disconnected, this means being controlled by thecondition of. thecalled I line, and. operating the; supervisory signal in one manner itthe line is; idle and in another manner if it is busy.

'lniore specifically, a *dialingcordf circuit common to the tollposition, is provided; a number of toll connecting circuits is alsoprovided. for each. position. Then the toll operator desires to set up atoll call to an: automatic, office; she inserts the calling plugs oiboth oi said circuits into a-Hpair of jacks. individual to the trunk.The trunk isthusextended illUOllgll contacts of a relay. in the trunk tothedialin the cord circuit. The operator now turns-the dial. to set theswitches at the automatic oiiice'. hen the connector is set on thecalled line the relay switches the trunk from the dial cord circuit tothe connecting; cir= (.'.-U.li' The line if idle causes the supervisorylamp in the connecting circuit to: light.,. and the busy conditiona oithe: line causes the signal to flash. The operator in the: former caseby depressing; a key causes tlie cone Hector to apply ringing current tothe selected line, Upon the: response oh the called party: the lampisextinguished.

Anothen feature is. the; provisionofmeans 192 Serial No. 481,747.

for automatically lighting a lamp in the cord circuit if any oi theselectors encounters a busy trunkgroupl vAnother feature is theprovision of a pair of coin control keys associated with the cordcircuit; and if the call is to or from. a pay station the operator afterthe response of the called party actuates the proper key to apply plusor minus cu'rrent to the trunk from her position. A relay atthe automatic oi'iice relays this current to the'line tooperate the coin hoxnagnet.

A further feature- ;is the provision of meansfor holding. the connectoron the line if it is busy, for causing the same to F seize such line assoon as it becomes idle, the seizure of the line causing the callingsupervisory lamp to cease flashing and re main steadily lighted as aringing signal tothe; toll operator, who thereupon actua'tes her ringingkey to start the automatic ringing. operation in the toll: connector,the ringing current being cut 0th and the talking circuit completed uponthe response of the called party.

Other features will. be. pointed out-Yin coin nection. with the detaileddescriptions Referring to the drawings, Fig. 1! shows a. combined.dialing. and coi-n cord circuit and. also apart 01- a connectingcircuit;- Fig 2 showsa toll switching trunk circuit; Fig.3 shows anincoming selector ;1 Fig. l shows a toll transmissionselector repeater;Fig. o-shows a toll connector; Fig. 6 shows a toll rotary connector.

The inventioir willbe-more clcarl y understood from a detaileddescription of the operations involved insctting up a connection.

The toil-l. operator haying received the number of the desiredsubstation from the recording, operator. or in any other suitablemanner, touches the tip 0t her plug 100 toflthe tip oi her jack 101', toselect" an idle. trunk leading to the automatic ofii'ce; and inserts:the'p'lug intov the jack. Relays 1'02; 200 thereupon operate over the"fol lowing circuit: free pole of battery, relays 102.103 condiicton1051; sleeves of the=plug and jach re'iay 200,.to ground. Belay 1053disconnects the busy test conductor and completes: the tip conductor,.and relay 200 prepares certain circuits Whichwill be described latter.Relay 103 is'marginal and does not operate in: this circuit, but onlywhen the plug 100 is inserted into atoll line. of her dial cord intojack 107, which causes relays. 108 and 201 to operate, the latterconnecting the trunk conductors 202, 203 to the conductors 204, 205leading to the operators dial 109. Relay 201 removes the short circuitfrom about the right winding of relay 206, and this relay operates for apurpose which will appear.

' Impulse relay 300 of the incoming selector at the automatic office nowoperates over the following circuit: free pole of battery, lower windingof relay 300, armature 308, and normal contact of relay 307, conductors306, 203, armature 209, and alternate contact of relay 201, conductor205, ring of the jack 107, ring of the plug 106, normal'contact of key120, conductor 121, relay 110, middle right armature and normal contactof relay 115, conductor 122, impulse contact 112 of the dial, conductor123, outer right hand armature and normal contact of relay 115, normalcontact of key 120, tip of the plug,

L tip of the jack, conductor 204, upper armature and alternate contactof relay 201,.conductors 202, 305, armature 309, and normal 'contactofrelay 307, upper winding of relay 300, normal contact of switch 304, toground. Relays300 and 110 operate'in this circuit. Relay 110 operatesslow relay 113 in a circuit including the innerright armature of relay115, and relay 113 in attracting its inner right armature locks itselfto ground at the armature and alternate contact of relay 108. Theimpulse relay 300 of the incoming selector in operating energizes theusual slow relay 301, which opens the circuit of release magnet 302, andprepares the circuit of vertical magnet 303 in the wellknown manner. Theoperator now turns the dial to transmitthe first digit of the desirednumber. Ofl-normal contact 114 on the dial operates relay 115 whichlocks through the armature and front contact of relay 108. At its middlearmature relay 115 opens the original energizing circuit of relay 110,but this relay remains energized in a circuit including the leftarmatureand front contact of slow relay 113. The dial restoring interrupts theloop including the impulse'relay 300 and the relay 110. The verticalmagnet 303 receives impulsesfrom impulserelay 300 in the well-knownmanner and raises the .selectorto the desired level, which automatically hunts for an idle trunk leading ,to a toll transmissionselector (Fig. 4). The operation of the incoming selector (Fig. 3), willnot be described in detail, since it is of the standard'type shown anddescribed for example in Patent No. 1,377,225 issued May 10, 1921 to A.J. Seymour. Relay 113 in the dial cord being slow, does not release, asits circuit is intermittently opened by relay 1.10. If, howeve theincoming selector The operator now inserts the plug 106 right armaturelights the all busy trunks lamp 116, whereupon the operator withdrawsplugs 100 and 106, and waits and sets up the connection later.

Assuming however that the incoming se le'ctor (Fig. 3),'finds an idletrunk, relay 307 operates and extends the trunk conductors 305 and306through to thetoll selector (Fig. 4), whereupon the impulse relay 400thereof operates over the following circuit: free pole of battery, leftwinding of relay 400, outer right armature and normal con" tact of relay401, normal left contact of relay 402, lower left-hand winding of therepeating coil RC to the lower talking conductor, over the path tracedto the dial cord,"returning over the upper talking conductor through theupper left-hand winding of repeating coil RC right normal contact ofrelay 402, inner right armature and normal contact of relay 401, rightwinding of relay 400, switch 404 to ground. The impulse relay of thetoll transmission selector and therelay 110 are energized in thiscircuit, the latter maintaining the slow relay 113 energized to preventthe lighting of the all trunks busy lamp 116, and the formeroperating'the usual slow relay 405 to interpose a break in the circuitof the release magnet 420 and prepare the circuit of the vertical magnet407. Relay 405 in attracting its inner right armature, grounds tlierelease wire 406 leading back to the incoming selec- Ltor to hold up therelay 307 after the slow relay, 301 releases in the wellknown manner.This ground also causes the seized toll transmission selector to testbusy. to other incoming selectors. The operator now turns thedial forthe next digit and upon the restoration of the dial, relay 400 transmitsimpulses to the vertical magnet 407 to raise the toll selector to thedesired level. The slow relay 412 in series with the vertical magnet 407operates a relay 421, this'eircuit including off-normal contact 422 andthe outer right armature and alternate contact of relay 405. Relay 421in attracting its left armature, locks itself over a circuit includingthe armature and normaleontact of magnet 423, and the inner armatureand. the normal contact of slow relay 424. Relay 412 also operates arelay 411, this circuit also including the outer right armature and normal contact of relay 405. This relay locks up in a circuit includingitsarmature 413 and the outer right armature of relay 405. .VVhen slowrelay 412 releases upon the termination of the vertical impulses therotary magnet 423 is operated over a circuit in- ,i'llG first trunk, andat the end of its stroke 1 opens the locking circuit or relay 421 whichreleases, opening the circuit of the rotary magnet in the \vel leknomnmanner.

grounded and: relay. r21 again operates over a circuit includingthe.oil? nor-meal switch 4:22, arinature and normal contact of the rotarymagnet, conductor 426, armature 4:17, outer right armature of relay4-24,, conductor 416. to the grounded-test multiple 425. Relay l21againv closesthe circuit of the rotary magnet and locks, up in thecircuit pro-yr. ,ously traced. The rotary mag-net steps the brushes to,the nezgt trunk.

This interaction between the relay 4-21 and magnet 423 co tinues; untilan. ungrounded test multiple is reached, whereupon. the relay 5:98operates over a, circuit includingrelay 42-1, swi h. 22, normal on ac omag-n t 4 23, conductor 4,26, relay 4,055, to ground at .the outer righta mat and m o t ofrelay 405, Relay 408 extends the con,- gluctors 4.09,410. to. the in' pulse relay 500 of the toll connectorwhich iia op ratesoyer the f ll "11;; circui pole f bat ery,

, M lne w o: conductor 5 12, arInatu 51-3 andynornral contact relay 59lower talking concluo tors (Figs. 5 and; 1), lower right winding ojfirepeating coil EC, left armaflrre anal trout contact 015 relay-all, leftW ling of relay 4e18, upper right wh rling oli the repeating coil RG,-upper talking. coudtrcto-rs l and 5);, arnrature 51:4 and normalcontact of relay 5 5. left winding of r c 5.00,, to, gr und. Rel y 1:1.is n eased. clue to the seizure of the toll connector since Contact ll lisI a IRQkBrbQillOIEwblfGfilfi cont-act. Relay 411 is; thus held; upoyer the. tel-lowing circuit: free polev of battery, relay l11,augngat-ure ll -3 vand its front; contac contact ll t, c n r l: l ad 1 cnduc 0, arm-rat-ure 515311161 normal cont-actor relay 505, sleeveconductors 5,06, 416', armaturell/Z, and altern Contact of relay 108-to, ground at the outer right armature of relay 1305. Then the loopcircuit was closed including t e letlt winding:- of relay 418, 1 circuitwas s1; iultaneously closed, through the right winding. 015 sa d relayat the lower-most arinat e and; front coutact 0t relay 408. These rindings neutralize. each otherand consequently relay 4:18 remains inert.Relay 500 operates slowrelay- 591' over a circuit including thevupperwinding of said relay and the lowerm st armature and back contact ofrelay 505. Relay 50]: in attrac ing its uppermost armature locks. itselfto the. sleeve Willj. 506 by Way of the armature 51 51 ofthe. relay5.05, and connects the terlli the, first trunk is busy, its test.multiple 425 is,

tical magnet 502 to. the hack contact of the impulse relay 5.90, andopens the circuit of release magnet 503. lfhe operalornorv turns thedial tor-the tens digit, and the relay lOO, the circuitof which; hasbeen preyigously traced repeats the impulses to relay 5,00 whichtransmits impulses to the ertical n egnct 502 to .l'ilh: theconnecdesrrctl level. The usual sloiv relay. is in series with therertical 711mg The first impulse tor the Yer-tical net passes lay way ofcontact 517 of t ell-normal switch 516, and; the succeeding inrpul scspass lay way of contact 5118, and the armature and front Contact 01 slowrelay 4307..

Upon the cessation of the vert' pulses, relay 50?; release, connec V. Nin let 508' to the back contact of tire impi: so relay 5G0; 'l-heoperatornom t the dial for theunits digit to rotate the brushes intocontact with the desired line. The slow relay 509 in series with therotary magnet upon its operation energizes slow relay 511(Jlfl-011'1 theground on the sleeae wire 5.06:. Relay 509 in attracting; its leftarmature operates relay 519 which loclts up to the sleeve Wire 506.-When relay 509 releases, its right ari-rrat-ui'e connects relay 5-11over the inner right armature of relay 510 which if the selected line isbusy, locks up to, the ground at its. test multiple. Relay 5111 operatesfrom this ground and reverses the direction of the current flow in, thetrunk leading back to the relay 418. in, the toll transmission selector(Fig. ll which causes the polarizecr relayllS. to GP! crate. Relay 18 atits armature 431,9- op" operates relay 402 fronr the ground at thelowermost armature of relay 1508. lie-lay e02 reverses the directionoli' current flow in the trunk leading back to: the dial and coin cordcircuit. This causes the polarized relay 111 to. operate, and ren oycsthe short-circuit from about relay 117, wherer upon the marginal relay201, releases, d;is connecting the trunk; 202, 2-03 from the dial cordand extending it to the connecting cord. Relay 4:37, being marginal doesnot operate at this time. Relay :1 in releasing locks up relay 206. andnovides a circuit for relay 208 which operates and closes. a break in,the ring conductor; The supervisory lamp 119 in the connecting circuitnow flashes. to in.- dicate the busy conditionv of the desired line.This is brought about in, the. 't'ollom 'ingrnianner: Relay 4:18 inattracting its innermost left armature, connects an interrupter 1-27 to.the lower Winding of relay 128, the circuit being as. follows:-innerimst armature of relay 4B8, lower-Winding o f the relay 4-28,armature 4:29, liront contact of relay all]; to ground at the leftarmature and: front contact 0:1 relay 4,00. Relay 228 in intermittentlyattract ng its armat re app ies a i it) wire 506. Relay 505 inattracting its arma ture 515 opens the circuit previouslytraced for therelay 411. Relay 411 in retracting its armature 429, opens the circuitincluding the interrupter 427 and relay 428, relay 428 remaining inert,causing the supervisory lamp 119 to remain steadily lighted. This servesas a ringing signal to 'the toll oper ator, who thereupon depresses herringing key RK to impress ringing current on the trunk to operate'relay432 over the trunk conductors in series. Relay 432 in attractingitsarmature operates relay 428 over a circuit including the armature433, lower winding of relay 428, armature 429 of relay 411, and armature434 of relay 413. Relay 42Siu attracting its armature 430 opens thecircuit previously traced for the relay 501 which releases and appliesringing current to the selected line. Upon the response of the calledparty, relay 501 operates in the wellknown manner and again locks up tothe grounded control lead 504 and completes the talking circuit. Relay435 now operates in series with the called line over the followingcircuit: free pole of battery, le'tt winding of relay 435, relay 436,left-hand armature and back contact of relay 411, lower right-handwindings of the repeating coil, lower talking conductor, returning overthe inner right armature of relay 411 to ground at the right winding ofrelay 435. Relay 436 operates relay 401 which in attracting its rightarmatures removes battery from the trunk conductors leading back to theconnecting cord, and the outer right armature closing a bridge to holdrelay 400 operated. The removal of battery from the trunk leading to theconnecting cord, releases the supervisory relay 118 1 which extinguishesthe lamp 119 indicatingto the operator that the called party hasresponded. Talking current is fed to the calling line over the windingsof the repeating coil at the distant otfice (not shown).

If the substation A to which connection has been made is a pay stationthe operator will communicate with the called party and inform him ofthe coins 'to be deposited. She checks this by the sound frpm the gongswhich the coins strike in passing through the chutes ot the coin box inthe line.

well-known manner. The operator now lfeinserts. the plug 106 intothewjack 107. Since relay does not operate until the dial is moved 003normal, relaylll is short circuited'and does not operate, consequentlyrelay 117 does not operate. Relay 201 however, operates to extend thetip and ring of the trunk to the cord circuit. The operator then'actuates key 120, which connects a 110 volt source of currentto thering of the trunk to operate relay 437 in the transmission selector. Thecircuit for relay 437 is as iollows: i'rec pole of battery, contact ofkey 120, ring of the plug 106, ring of the jack 107, ari'nature 209 ofrelay 201., ring conductors 203, 306, armature 308, alternate contact ofrelay 307, ring conductors Figs. 3 and 4), lower left winding of therepeating coil RC, conductor 438,

left armature and alternate contact of relay 402, relay 437 anditsnormal contact,c0nductor 439, inner right armature and front contactof relay 401, conductor 440, right arm ature and front contact of relay402, conductor 403, upper left winding of the re peating coil RC, uppertalking conductor (Figs. 4, 3 and 2), upper armature and alternatecontact of relay 201, conductor 204, tips of the jack and plug, contactof key 120, conductors 124, 125, normal contact of key 126, conductor127, normal contact of key 128 to ground. Relay 437 in attracting itsarmature 441 locks itself to ground, and in attracting its armature 442transfers the tip of the trunk from its normal connections to the tipand ring of the called It the called subcribers receiver is on theswitchhook, the operating circuit for relay 437 leads through the rightwinding of relay 400 to ground. Key 120 while actuated remains in itsactuated position until released by the operator. The operator nowdepresses one of the coin keys 126 or 128, which will impress plus orminus 110 volts upon the tip of the trunk. Relay 437 being operated,permits this current to flow over the talking conductors in parallel toground, through the polarized magnet in the coin box. This coin box maybe of the type shown and described in Patent No. 1,043,219, issued Nov.5, 1912 to O. F. Forsberg. The deposit of the minor coins connects thepolarized magnet to ground. this ground is present, relay 130 in thecord circuit will operate, lighting the lamp 131 to indicate to theoperator the condition of the circuit; that is to say, if no coins havebeen deposited, relay 130 will not operate and the lamp 131 will notglow. The "release of the coin key in releasing the magnet causes themagnet to disconnect itself from ground, thus opening the circuit ofrelay 130, which extinguishes the lamp 131. The operator new releasesthe key120, whereupon the relay 437 restoresand completes the talkingcircuit in the transmission selector.

The operator now withdraws the plug 106 whereupon the relay 201releases, completing the talking circuit at the trunk (Fig. 2). Thesubscriber at substation A by actuating his receiver hook causes relay$36 to intermittently operate relay 401, which applies and removesbattery from the trunk, thus intermittently operating the relay 118to-flash the lamp 119. Inasmuch as relay 1-00 is holdup either throughthe bridge in eluding the resistance when. the receiver hook is up, orover the trunk leading back to the connecting cord when the receiverhook is down, relay 105 is maintained energized to prevent release.

l Vhen the party at substation A restores the receiver, relay 436releases, releasing relay 401 which replaces battery on the trunkoperating relay 118 to light the lamp 119. When the operator desirestobreak down the connection she withdraws the plug from jack 101 whichplaces relay 210across the trunk by the release of the left armature ofrelay 20.0. Thus, and if the subscriber's receiver is still off thehook, there will be no battery on the trunk, and relay 210 will notoperate, Relay 208 remains operated to apply battery through its outerarmature and the inner right armature of relay 200, to the sleeveof thejack 101 to cause, this trunk to test; busy. lVhen the subscriber hangsup. his receiver, battery is applied to the trunk as described, whichauses rel-a 210 to operate to open the looking circuit of relay 208,whereupon relay 208 releases, opening the loop circuit including relay210 which releases relay 400, and since the relay an is at thistimevinert due to the subscriber having replaced his receivcr,-relay 105 isreleased. Relayl05 at its inner right armature removes ground from thesleeve wire 4106 to deenergize switching relay 307. This relay at itsuppermost armature closes the circuit of release .niagnet 302 to restorethe incoming selector. The retraction of the left armatures of relays4-05 and Q00 operates the release magnet 420 of the transmissionselector. The release of the transmission selector releases relays 505,501 and 519. Release of the relays 505 and 501 completes the circuit forthe release magnet 503 of the connector from. free pole of battery,magnet 503, off-normal switch 516, lower- ;iost armature, and normalcontact of relay 601, left armature and back cont-act of relay 500,lowermost armature and normal contact of relay 505 to ground.

Referring now to Fig. 6, it shows a toll rotary connector, that is tosay, a connector wherein private branch exchange lines terminate. Thiscircuit isso arranged that if all thetrunks correspoi'iding to the,called number are busy, the switch will wait in front of the trunkgrou aand cause the supervisory lamp 119 to flash. When one of these trunksbecomes idlethe switch will move along the bank and seize this. trunkautomatically, and upon the seizure of such trunk will cause the lamp119 to remain steadily lighted as a ringing signal. The operator willthen depress her ringing key and-cause a ringing operation to start. Theremaining operations are the same as those traced in connection with thetoll connector. The operations involved in raising the toll rotaryconnector to the desired level are exactly the same as those describedin. the case of thetoll connector, the relay 600 trans, mittingiinpulses to the vertical magnet 602 and the relay 607 Onthe terminationof these impulses closing the circuit of rotary magnet 608. The rotarymagnet then in response to impulses from the impulse. relay 600 rotatesthe brushes to the first trunk. Slow relay 609 energizes upon the firstro- ,tary impulse and operates relays 610, 620, and 619. Relay 619 looksup to the. sleeve wire 606. If all trunksare busy, a series of chainrelays 621, 622 etc. extends the ground on the last test multiples 628,624 to the multiple 626. Relay 610 at its. inner left armature locks upto ground at multiple 625, and at itsinner right armature holds relay620 operated from the ground on testmultiple 626 to prevent the switchfrom stepping. Relay 610 at its. outer right armature operates relay 611over the following circuit, free pole of battery, relay 611, leftarmature and front contact of relay 620, outer armature and frontcontact of relay 610, lower armature and front contact of relay 6.19,left armature of relay 609 to ground on the sleeve wire 606. Relay 611reverses, the direction of current flow in the trunk leading back to therelay e18, just as in the case of a busy ordinary line, whichrelay 4-18-in operating, connects the interrupter in. circuit with the relay 128,which intermittently applies ground in shunt of the supervisory relay118 to flash the lamp 119 before the toll operator. As soonas one of thetrunks becomes idle a chain relay releases disconnecting the ground fromtest multiple 626. which causes the release of relay 620. If this idletrunk is the one upon which the switch is resting the removal of theground from its test multiple 625 releases the slow relay 610, whereuponthe relay 605 operates over the following circuits: free pole ofbattery, relay 605, outer right armature of relay 610, lower armatureand front contact of relay 619, left armature and back contact of relay609 to ground on the sleeve wire 606. Relay 605 in attracting itsuppermost armature releases relay 4111 of the toll transmission selectorwhich in retracting its outermost right armature holds relay 402operated independently of relay 118, and in 620 to the relay 627, relay610 remaining locked up on this ground over its left winding. Relay 627in attracting its left armature locks up over the backcontact of therotary magnet 608, and at its right armature transmits an impulse tothis magnet; The

rotary magnet at the end of its stroke-opens the locking circuit ofrelay627, which in releasing its right armature, opens the circuit of therotary magnet; This interaction continues, and the rotary magnet stepsthe switch aroundnntil it reaches the ungrounded test multiple 628,whereupon relay 610 releases, operating relay 605, with the resultsdescribed. The operator in re sponse to the lighting of the lampoperates her ringing key, which energizes relay 432 to operate relay428, which'in attracting its armature 430, releases relay 601 to startthe automatic ringing operation. The remaining operations are the sameas those described in the case of the toll connector.

hat is claimed'is:

1. In a telephone system, a trunk terminating at one end in a pair ofjacks and at the other end in an automatic switch, other automaticswitches, a cord circuit and a connecting circuit for connection withsaid jacks respectively, a dial associated with said cord circuitfor-settingsaid switches, means for automatically disconnecting saidtrunk conductors from the cord circuit and con necting the same to theconnecting circuit upon the selection of the called line, and means formaintaining the setting of the switches after said transfer from thecord circuit to the connecting circuit has'taken place. p

2. In a telephone system, atrunk terminat ing at one end in a pair ofjacks and at the other end in an automatic switch, other automaticswitches, a cord circuit and a connecting circuit for connection withsaid jacks respectively, a dial associated with said cord circuit forsetting said switches, means for automatically disconnecting said trunkconductors from the cord circuit and connecting the same to theconnecting circuit upon the selection of the called line, means formaintaining the setting of the switches if the called line is in busycondition, a supervisory; signal, a supervisory relay in the connectingcircuit, and means controlled :by the idle condition of the called linefor operating said relay to control said signal.

3. In a telephone system, a trunk terminating at one end'in a pair ofjacks and at the other end in an automatic switch, other automaticswitches, a cord circuit and a connecting circ'uitfor connection withsaid jacks respectively, a dial associated with said cord circuitforsetting said switches, means for automatically disconnecting said trunkcon ductors from the cord circuit and connecting the same to theconnecting circuit upon the selection of the called line, a supervisorysignal, a supervisory relay in the connecting circuit, means actuatedbythe busy condition of the called line for causing said supervisoryrelay to operate said signal in one manner, means actuated by the idlecondition of the called line for causing said supervisory relay tooperate said signal in another manner and means for maintaining the setting of the switches regardless of the busy or idle condition of thecalled line.

4. In a telephone system, a trunk terminating at one end in a pair ofjacks and at the other end in an automatic switch, other automaticswitches, a cord circuit and a connecting circuit for connection withsaid jacksrespectively, a dial associated with said cord circuit forsetting said switches, means for automatically disconnecting said trunkconductors from the cord circuit and connecting the same to theconnecting circuit upon the selection of the called line, a supervisorylamp, a supervisory relay in the connecting circuit, means actuated bythe busy condition of the called line for causing said supervisory relayto flash said lamp, and means actuated by-the idle condition of thecalled line for causing said supervisory relay to steadily light saidlamp. 5. In a telephone system, a trunk terminating at one end in a pairof jacks and at the other end in an automatic switch, other automaticswitches, a cord circuit and a connecting circuit for connection withsaid jacks respectively, a dial associated with said cord circuit forsetting said switches, means for automatically disconnecting said trunkconductors from the cord circuit and connect ing the same to theconnecting circuit upon the selection of the called line, a supervisorylamp, a supervisory relay in the connecting circuit, means actuated bythe busy condition of the called line for causing said super visoryrelay to flash said lamp, means actuated by the idle condition of thecalled line for causing said supervisory relay to steadily light saidlamp, and manual means in said connecting circuit adapted when actuatedto cause ringing current to be applied to the called line from saidconnector.

6. In a telephone exchange system, a toll board, an automatic office, atrunk having two conductors only terminating at said board in a pair ofjacks, and at said automatic ofiice in a selector, other automaticswitches, a cord circuit and a connecting circuit at said toll board forconnection with the jacks respeccuit, a supervisory lamp, meanscontrolled by the busy condition of the desired line for causing saidrelay to flash said lamp, means controlled by the idle condition of theselected line for causing said relay to steadily light said lamp meansactuated by the operator to cause ringing current to be applied to theselected line, and means actuated by the response of the called partyfor disconnecting said ringing current. and extinguishing said lamp. g

13. In a telephone system, an operator's position, a trunk terminatingthereat in a jack and at its other end in a selector, other automaticswitches, a cord circuit and a connecting circuit for connection withsaid jacks respectively, a dial associated with the cord circuit forsetting said switches, a relay in the trunk-operated upon the connectionof the cord circuit to the trunk to connect the trunk conductors to thedial, a resistance in the cord circuit normally short-eircuited, a relayoperated upon the selection of the desired line to remove the shortcircuit from about said resistance to cause said relay to release andconnect said trunk conductors to said-connecting circuit, a supervisoryrelay in said connecting circuit, a supervisory lamp, means'controlled'by the busy condition of the desired line for causing saidrelay to flash said lamp, means controlled by the idle condition of theselected line for causing said relay to steadily light said lamp, meansactuated by the operator to cause ringing current to be applied to theselected line, nieans actuated by the response of the called party fordisconnecting said ringing current and extinguishing said lamp and-meansc011- trolled by replacement of the receiver by the called party. forlighting said lamp.

14. In a telephone system, an operators position, a trunk terminatingthereat in a jack and at its other end in a selector, other automaticswitches, a cord circuit and a connecting circuit for connection withsaid jacks respectively, a dial associated with the cord circuit forsetting said switches, a relay in the trunk ope-rated upon theconnection of the cord circuit to the trunk to connect the trunkconductors to the dial, a resistance in the cord circuit normallyshort-circuited, a polarized relay in said cord circuit controlling saidshort circuit, and means actuated by the selection of the called linefor reversing thecurrent flow through said relay to operate the same toremove said short circuit from about said resistance to cause said relayin the trunk to release and connect said trunk conductors to saidconnecting circuit.

15. In a telephone system, a trunk terminating at one end in a manualswitch and at its other end in an automatic switch, other automaticswitches, a cord circuit ter:

' place.

minating in a manual switch for connection with the manual switch of thetrunk, a

associated with said trunk after thetrausfer oi the trunk from thecordcircuit to the connecting circuit.

16. In a semi-automatic telephone system, telephone lines, a cordcircuit, trunk lines accessible thereto, a calling device adapted to beassociated with said trunlccircuit by meansof said cord circuit, aconnecting circuit, and means controlled by the selection of the calledline for auton'iatically disconnecting said calling device from saidtrunk circuit, and for connecting said trunk circuit. to said connectingcircuit and for maintaining the called line connected to saidtrunk afterthe transfer from the cord circuit to the connecting circuit has taken17. In a semi-automatic telephone system, telephonelines, a cordcircuit, a trunkcircuit, a dial, manual means for associating said dialwith said trunk, automatic switches controlled by said dial forextending the trunk circuit to a telephone line, a connecting circuithaving a supervisory signal,

a means controlled by the idle condition of the called line forautomatically disconnecting sa d dial from said trunk and operating saidsupervisory signal and means controlled by the busy condition of theconnected telephone line for automatically disconnecting said dial andmaintaining the telephone line connected to said trunk.

18. In a semi-automatic telephone system, telephone lines, a cordcircuit, a. trunk cir cuit, a dial, manual means for, associating saiddial with said trunk, automatic switches controlled by said dial forconnecting a trunk circuit to a telephone line, a connect-- ing circuithaving a supervisory lamp, means controlled by the busy condition of theltll) llO called line'for automatically disconnecting said dial fromsaid trunk and flashing said lamp and maintaining the called line connected to said trunk.

19. In a telephone system, a toll trunk terminating at one end in amanual switch and at its other end in an automatic switch, otherautomatic switches including a 0011-. nector, private branch exchangetrunks terminating in said connector, a cord circuit terminating in amanual switch for connection to the manual switch of the trunk, aconnecting circuit, a. dial associated with said cord circuit, and meansfor automatically disconnecting the trunk conductors from the manualswitch of the trunk and for connecting the trunk conductors to saidconnecting circuit upon the selection of the first private branchexchange trunks.

20. In a telephone system,atrunk terminating at one end in a manualswitch and at its other end in an automatic switch, other automaticswitches including a connector, private branch exchange trunksterminating in said connector, a cord circuit terminating in a manualswitch for connection to the manual switch of the trunk, a connectingcircuit, a dial associated with said cord circuit, means forautomatically disconnecting the trunk conductors from the manual switchof the trunk and for connecting the trunk conductors to said connectingcircuitupon the selection of the first private branch exchange trunks, asupervisory lamp in said connecting circuit means whereby said connectorautomatically tests said private branch exchange trunks, and meansoperated upon the selection of an idle private branch exchangetrunk forlighting said supervisory lamp.

' 21. In a telephone system, a trunk terminating at one end in a manualswitch and at its other end in an automatic switch, other automaticswitches including a connector, private branch exchange trunksterminating in said connector, a cord circuit terminating in a manualswitch for connection to the manual switch of the trunk, a connectingcircuit, a dial associated with said cord circuit, means forautomatically disconnecting the trunk conductors from the manual switchof the trunk and for connecting the trunk conductors to said connectingcircuit upon the selection of the first private branch exchange trunk, asupervisory lamp in said connecting circuit, means whereby saidconneetor automatically tests said private branch exchange trunks, meansoperated upon the selection of an idle private branch exchange trunk forlighting said supervisory lamp, and means automatically operated if allthe private branch exchange trunks are busy for flashing saidsupervisory lamp.

22. In a telephone system, a trunk terminating at one end in a manualswitch and at its other end in an automatic switch, other automaticswitches including a connector, private branch exchange trunksterminating in said connector, a cord circuit terminating in a manualswitch for connection to the manual switch of the trunk, a connectingcircuit, a dial associated with said cord circuit for setting saidswitches means for automatically disconnecting the trunk conductors fromthe manual switch of the trunk and for connecting the trunk conductorsto said connecting circuit upon the selection of the first privatebranch exchange trunk a supervisory lamp in said connecting circuit,means whereby said connector tests said private branch exchange trunks,means operated upon the selection of an idle private branch exchangetrunk for lighting said supervisory lamp, means automatically operatedif all the private branch exchange trunks are busy for holding theconnector set on the first trunk and for flashing said supervisory lamp,and means operated when one of the private branch exchange trunksbecomes idle for causing the connector to select and seize the same andfor steadily lighting said lamp.

In witness whereof, I hereunto subscribe my name this 28th day of JuneA. D., 1921.

RAY L. STOKELY.

